PHYSICAL AND FUNCTIONAL INDEPENDENCY OF P70 AND P58 NATURAL-KILLER (NK) CELL RECEPTORS FOR HLA CLASS-I - THEIR ROLE IN THE DEFINITION OF DIFFERENT GROUPS OF ALLOREACTIVE NK CELL CLONES

Natural killer (NK) cells express clonally distributed receptors for d ifferent groups of IFLA class I alleles. The 227 monoclonal antibody d escribed in this study recognizes a p70 receptor specific for HLA-B al leles belonging to the Bw4 supertypic specificity. Single amino acid s ubstitutions in the peptide-binding groove of HLA-B2705 molecules infl uenced the recognition by some, but not all, p70/Z27(+) clones. This s uggests the existence of a limited polymorphism within the p70 family of receptors. The pattern of reactivity of monoclonal antibody Z27 rev ealed that Bw4-specific receptors may be expressed alone or in combina tion with different (GL183 and/or EB6) p58 molecules. Analysis of NK c lones coexpressing p58 and p70 receptors allowed us to demonstrate tha t the two molecules represent physically and functionally independent receptors. The expression of p70 molecules either alone or in combinat ion with EB6 molecules provided the molecular basis for understanding the cytolytic pattern of two previously defined groups of ''alloreacti ve'' NK cell clones (''group 3'' and ''group 5'').